The present invention pertains to toilet flush valves, and more particularly to flush valves of the type using a tank ball that is lifted off its annular seat and then subsequently descends as the tank empties, until it reseats on the valve seat.
Flush valves of the type described have been in widespread use for decades, and while they usually work satisfactorily for the first few years after being installed, they almost invariably become troublesome in time, due to lime deposits on the tank ball rod, and excessive wear in guides that are supposed to center the tank ball with respect to its seat as the ball descends. As a result, the tank ball either hangs up or fails to seat accurately, so that the tank continues to drain until the toilet handle is jiggled, or the tank ball is lifted manually and dropped onto its seat.
The problem is that the guides for the tank ball rod are so closely spaced or otherwise constructed that they have only a short length of sliding contact with the rod--usually only an inch or so. As the rod becomes encrusted with lime deposits, it becomes rough and abrasive, and repeated sliding motion of the rod through the guide holes causes wear, enlarging the guide holes. As the guide holes become enlarged, the guiding action becomes increasingly inaccurate, with the result that the tank ball is frequently dropped onto its seat off center. At other times, the tank ball rod will become canted at a slight angle in the enlarged holes of the guide, so that it hangs up and cannot drop back onto its seat. These malfunctions are the cause of many expensive repairs by plumbers, and are the source of much inconvenience and annoyance to the householder.